The Computer Between the Ears

[wetb4igetinthewater]

Pattern recognition.

It is quite possible to train your subconscious to recognize ascent patterns for various dive profiles, you just have to dive a lot. Then you could express them as, say, ratios. But while you're training it, ascents have to be calculated by some other computer.

And then you've trained your brain to follow whichever model that dive planner was using. So if you used the one that generates deeper stops, your brain now wants to make deeper stops. If that is no longer advisable -- re-training the brain takes forever and the older we get, the harder it gets.

There might be a human out there capable of keeping track of 16 tissue compartments simultaneously in his head, but I'm sure most of us are not him. Brain is not running the same model and all those comparisons to computers are bit of apples to Pink Floyd.

And add in an emergency and all that goes out the window (I think it is a stretch, but my academic background is in audio/video/image algorithms where an understanding of human perception is needed, but not a full blown knowledge of the latest brain research).

As someone told me once, dive computers are impervious to stress

 

[boulderjohn]

And add in an emergency and all that goes out the window (I think it is a stretch, but my academic background is in audio/video/image algorithms where an understanding of human perception is needed, but not a full blown knowledge of the latest brain research).

As someone told me once, dive computers are impervious to stress

Two years ago a friend of mine got into a horrible situation during a dive. On more than one occasion over a span of time he thought he was going to die. His buddy did die. While trying to deal with the buddy's death, he realized that he had to think first about his own survival. He checked his computer and saw that he had accumulated a ton of deco, much more than expected. He therefore abandoned that work and began his ascent.

I am not sure what he would have done if he had been of the school advocating keeping a running average depth in his head and then computing his ascent profile based on that average. He might have had a hard time doing that while fighting for his life.

On a discussion similar to this a number of years ago, one of the participants said he liked to follow the "compute your average depth/calculate your ascent" process because it gave him something to think about during the dive. Sometimes you have other things to think about.

 

[Jack Hammer]

It's a bit of a semantics issue and, I believe, very misunderstood by many. I was taught to use the computer in the head and to not rely solely on the computer on my arm. That did not mean to not to use a dive computer at all. It meant to not just blindly jump in the water and follow a dive computer letting it manage your entire dive profile and waiting for it to tell you what to do and when.

 

[boulderjohn]

It's a bit of a semantics issue and, I believe, very misunderstood by many. I was taught to use the computer in the head and to not rely solely on the computer on my arm. That did not mean to not to use a dive computer at all. It meant to not just blindly jump in the water and follow a dive computer letting it manage your entire dive profile and waiting for it to tell you what to do and when.

During my first 4-5 years of technical diving with two agencies and with Lord knows what agencies the other people on the boats were using, I only saw someone use a computer one time that I can remember. I heard the mantra telling me that "We don't use computers--computers are bad" expressed in different ways many times.

 

[wetb4igetinthewater]

I am not sure what he would have done if he had been of the school advocating keeping a running average depth in his head and then computing his ascent profile based on that average.

John,

Good chance he’d be dead. I can’t speak for all dive computers, but I can configure my Shearwater (which is how it is set) the dive time. If someone wants to do RD, fine, they can, but why not have the dive computer as a sanity check/emergency backup? I really don’t understand.

 

[LiteHedded]

Two years ago a friend of mine got into a horrible situation during a dive. On more than one occasion over a span of time he thought he was going to die. His buddy did die. While trying to deal with the buddy's death, he realized that he had to think first about his own survival. He checked his computer and saw that he had accumulated a ton of deco, much more than expected. He therefore abandoned that work and began his ascent.

I am not sure what he would have done if he had been of the school advocating keeping a running average depth in his head and then computing his ascent profile based on that average. He might have had a hard time doing that while fighting for his life.

On a discussion similar to this a number of years ago, one of the participants said he liked to follow the "compute your average depth/calculate your ascent" process because it gave him something to think about during the dive. Sometimes you have other things to think about.

i mean, was his depth wildly different than what he planned the dive based on? if not, the avg was probably what he thought it was, or close enough for government work.

I've done a great many big-ish dives whilst calculating average depth in my head. sometimes dives where things went pretty sideways. it was never a big deal.

 

[Michael Guerrero]

a digital bottom timer is a computer. I don't dive without a computer of some kind because I can't tell time with my brain.

 

[wetb4igetinthewater]

I've done a great many big-ish dives whilst calculating average depth in my head. sometimes dives where things went pretty sideways. it was never a big deal.

Do you think having your dive buddy lose his life is in the ballpark of “pretty sideways“?

 

[boulderjohn]

i mean, was his depth wildly different than what he planned the dive based on? if not, the avg was probably what he thought it was, or close enough for government work.

I've done a great many big-ish dives whilst calculating average depth in my head. sometimes dives where things went pretty sideways. it was never a big deal.

They were ascending a very steep and challenging tunnel. I am not 100% certain of the total ascent distance of the survivor during the ordeal, but it was a minimum of 30 feet and probably more like 40 or more because at one point he retreated deeper in an attempt to assist. I don't know how long that portion of the dive took, but a lot happened so it would not surprise me if it was at least 10 minutes, with different amounts of time spent at different depths during that time. It was particularly challenging at a depth of 187 feet. This would have been all done in absolute zero visibility, as evidenced by a GoPro. Both divers had to work very, very hard during this time, and the CO2 buildup was tremendous. Panic was very much an issue.

If it would be no big deal to you to calculate your average depth and derive an appropriate ascent plan, then you are clearly different from me. I will confess that I would not be all that cool about it and would prefer to have the computer tell me what to do.

 

[TrimixToo]

Y'know, this entire discussion reminds me strongly of how some racers talk about how unnecessary antilock brakes are for them. You can learn to threshold brake. You can learn how to modulate the brakes for different conditions of temperature and wetness or dryness. You can learn how it changes back to normal gradually after enough traffic has past *after* it's dried following a good rainstorm. And, if you threshold brake often enough under all these conditions (and I mean more than daily) you can usually--but not always--outbrake an ABS. All this is demonstrably true.

On the other hand, ABS is very good, and it's consistent across a wide range of conditions. "Stomp and steer" gets you into the 90th+ percentile without having a last name that's "Unser" or "Schumacher." Every. Single. Time.

Does this mean you shouldn't look ahead? Not visually clear your path? Not visually evaluate escapes and responses in case (when!) that car ahead does something stupid? Not understand the approximate range of executable escape maneuvers? Of course not.

Let's face it. Off the track, with the variables that exist in surface condition every day, ABS is going to at least nearly equal and most likely outperform your braking performance on the average no matter how good you are. It will do that when you are tired. It will do that when you were momentarily distracted by the kids screaming in the back seat. It will do that when you are chock full of adrenaline, when you are blinded by lights or rain, and when you didn't see that ice patch.

Let's all watch where we're going and have a plan, by all means. Let's be thoughtful behind the wheel and under water and know when things are amiss and what to do, in general, to improve our chances. But let's use the tools at hand to improve our safety when it makes sense, too, instead of over-relying on our perfect execution of every unexpectedly necessary thing that has to be done right, right now.

Just another 2 PSI. (How'd that soapbox get down there?)